Solenoid valves of this type are used in motor vehicles in particular, for example, in fluid-regulated heat exchangers of their heating and/or air conditioning systems or as switching valves that short-circuit a coolant stream from an internal combustion engine of the motor vehicles in one of the two switch settings and in the other guide it across a heat exchanger. The solenoid valves may be activated by clock pulses as a function of the particular temperature in the heating and/or air conditioning system or in a passenger compartment of the motor vehicle, the flow rate being essentially determined by the mean time area. The valve member is opened by the fluid pressure and/or a valve spring acting on a valve shaft and is closed by excitation of the magnet coil acting on the armature. The space in which the armature is situated is not hermetically sealed but is instead filled with fluid. This fluid is intended to dampen the movement of the armature hydraulically in order to prevent the valve from opening or closing abruptly, thus reducing the noise associated with this. Due to the relatively large play required between the armature and the guide bushing for equalizing the tolerance between the components of the entire valve, the hydraulic damping produced by the fluid and accordingly the noise-reducing effect is, however, relatively low.
To reduce the noise produced when closing the valve, the applicant in European Published Patent Application No. 0 958 155 already described providing means on the side of the valve shaft facing the valve member which decelerate the speed of the valve shaft when the valve member is closed. Such means may be, among other things, formed by a damping disk which is attached to the valve shaft and is guided with low play in a fluid-filled chamber of the valve housing. Each time the valve member moves, the fluid must flow through a narrow annular gap between an outer circumference of the damping disk and an adjacent wall part of the valve housing, which slows the movement of the valve shaft. However, the provision of the damping disk and the chamber result in increased expense in manufacturing the solenoid valve. In addition, relatively close tolerances must be adhered to, which is difficult if low-priced components are used due to the temperature differences of the fluid when operating the valve in heating and/or air conditioning systems.